Definition of paternity: history and the present of
Questions of doubtful paternity, not clear family accessory and the most different problems resulting from this concerned people always. World history is full plots about unknown fathers, the hidden relationship, the separated families stolen and the changed well-born babies who died and revived years later tsarevitches... Who knows how there would be a history, there are no impostors in it? As for literature and cinema, everyone will remember a set of examples - from mythological plots to the Indian movies. Problems differently were solved. To king Arthur, for example, for the proof that he really the king`s son, was required to take out only a sword from an anvil (what the mere mortal could not make). And the wise decision of the tsar Solomon to award the disputable child to that woman who preferred to lose the son, but not to halve it, perhaps, on accuracy will not be inferior to genetic examination. The hero of the play “Filumena Marturano“ memorable to people of the senior generation and the movie “Marriage in Italian“ put on it tries “to find“ the son among three young men, painfully comparing their singing and business abilities; today it would not be required (but we would lose a touching plot).Real life offers
not less various collisions in which the modern genetics helps to place points over i.With what everything began
Before beginning conversation on definition of relationship, we will specify some terms. Speaking about the inherited signs, we do not mean external lines. Certainly, nobody disproves similarity of relatives, but it is well known that it can be and casual (“doubles“). External signs though they also are under control of genes, are unreliable for establishment of relationship. The majority of them are inherited difficult and controlled by many genes forming new combinations at children. It belongs not only to quantitative signs, such as growth, but also to qualitative, such as hair color and eye. Was considered, for example, earlier that at blue-eyed parents the brown-eyed child, however and it not so cannot be born.
, of course, very bright family “signs“ which are transferred from generation to generation Happen. The well-known “Habsburg lip“ - the unusual feature of a structure of jaws imprinted in portraits of representatives of a dynasty Gabsburgov throughout several centuries can be an example. But if existence of a similar rare sign testifies in favor of relationship, then its absence does not disprove relationship at all. In genetic literature the case of the claim made by the child`s mother with a special rare structure of fingers taking place in Norway - a brakhidaktiliya is described (shortening of fingers, is more often on one hand, due to shortening of average phalanxes). The defendant denied paternity, but when at court session hands asked to show it, it appeared, as it has a brakhidaktiliya. He was recognized as the child`s father; the sentence was based that the brakhidaktiliya is defined by a gene which can be transferred from generation to generation and meets so seldom that the probability of paternity of other man with the same gene is extremely small. At the same time lack of a brakhidaktiliya at the child would not exclude paternity, but would not allow to pass the decision without other proofs. Such case is casuistry, and the modern court would hardly be satisfied with this proof.needed to find
such signs which are rather easily defined and strictly submitting to laws of heredity which have not one or two, and several independent options which are found at different people. In 1900 the Austrian scientist Landshteyner opened existence of blood types (widely known I-IV groups). This opening not only allowed to develop a method of safe blood transfusion, but also uses of genetic data in forensic medicine for identification of the personality and genetic relationship became the beginning of several directions in genetics, including. Later other systems of blood types which are not of great importance for transfusion (except for the Rhesus factor system), but found application in genetic researches were open. The system of immunological characteristics - anti-genes of fabric compatibility of HLA having many individual options was one more help in diagnostics of relationship.
the Examination of disputable paternity based on comparison of the child and alleged father on such signs in many cases allows to reject paternity unambiguously: the child has such genes of blood types which he could not inherit from this man. But definitely it is not possible to prove relationship, and confirmation of relationship has probabilistic character: yes, the man of X can be the father of the child of Y, but any other man with the same option of the found signs can be him also. The probability of casual coincidence depends on the frequency of this or that option (or their certain combination) among the population. As the quantity of various blood types is not so high, the insufficient accuracy of examination even when using several systems could not suit either experts, or their “clients“.the Most modern methods of definition of paternity
Modern molecular genetics are developed and introduced by
in daily practice of many countries high-precision methods of identification of the personality and establishment of biological relationship on the basis of the analysis of DNA. Genetic examination of relationship includes research at alleged relatives of these or those signs which are defined only by sequence of DNA (deoxyribonucleic acid - the carrier of hereditary information in an organism; chains of DNA form in a kernel of each cage of an organism genes, and of genes - chromosomes). Methods are based by
that in DNA of the person there are many so-called polymorphic loci (loci - DNA fragments), that is the sites having numerous (to 8 - 12) options of sequences of DNA - Such loci call polymorphic (options of one locus are called alleles).
the Value of alleles for different genetic researches, including for examination of relationship, is defined by their invariance during life, strict transfer of parental alleles to posterity and a set of options of combinations of alleles. Definition of a set of alleles for several polymorphic loci (for example 10) at the specific person allows to receive for it some kind of individual “genomic card“. Research of polymorphic loci (as well as other “purely“ hereditary signs) is not capable to distinguish only one-egg twins whose molecules DNA are identical. In other words, the DNA method - diagnostics is based on comparison of certain sites of DNA of the alleged parent and child.Use of polymorphic loci (them DNA - markers also call) delivered to
examination of relationship on absolutely new level. According to the international requirements, not less than nine polymorphic loci are analyzed that allows to reach very high precision. When carrying out examination of paternity two results are possible. The negative result - a paternity exception - is 100%; such conclusion becomes at discrepancy not less than three loci. The positive result - confirmation of paternity, - as well as when using other methods, has probabilistic character, but the size of a mistake is incomparable below and makes the 100-th shares of percent. The paternity is considered established at reliability of the analysis not less than 99,999% (probability of casual coincidence 1 on 100 thousand people). Thus, the probability practically does not differ from 100%, and the positive result is so legally full as negative.
For DNA - the analysis of small enough very amount of biological material. The blood taken from a vein is most suitable for research, but if it cannot be received, use blood spots on filter paper (if blood is taken specially) or any other remained spots. Also cages of a soskob from an internal surface of cheeks, nails, hair approach. Prenatal expertize is carried out, naturally, with fetal material. For this purpose take amniotic waters (amniotsentez) or blood (kordotsentez) of a fruit. These procedures provodat in a hospital under ultrasonography control - puncture a forward belly wall, a uterus, at a kordotsenteza - an umbilical cord, the syringe take away material. The intake of material can be complicated by pregnancy interruption threat. If it is about posthumous examination, use the samples of fabrics which are stored at pathologists after opening (also preparations suit for microscopy). The term of carrying out the analysis - no more than two weeks, and if necessary - about three days.are continuously improved by
of Technology of research DNA. The last achievement was creation of the so-called chips allowing to carry out very quickly the simultaneous analysis of many indicators in one sample of DNA - This technology which was not widely adopted yet, obviously, will allow to reduce the cost of researches.
Why examination can be required?Examination of motherhood differs in nothing in
from examination of paternity, just need for it arises much less often. However, cases of mistakes with accessory of newborns in maternity hospital are known. Let`s not frighten future parents - it happens extremely seldom. Let`s remember, however, history about which wrote newspapers: the children who were born in one day in the same maternity hospital grew in the families living in the neighbourhood. Several years later obvious similarity of both girls not with parents, and with neighbors induced families to carry out diagnostics of biological relationship, and the guess about the occurred confusion was confirmed.the Most frequent reason of examination by definition of court - a question of the alimony, however also other situations are frequent
. Emigration, especially can become an official reason for carrying out examination if there are divergences in documents and a real-life situation. Embassies of some countries demand confirmation of biological relationship in case of departure on permanent residence or when homecoming the citizens who were long living in other country and got there a family.
it is frequent cancellation or preservation of marriage, destiny of pregnancy depends on examination. Sometimes the pregnant woman brings for examination of several candidates - consistently, and even together.
Here absolutely other example: young mother refused the illegitimate newborn, having left him in maternity hospital, but the alleged father, too absolutely young, decided to bring up the child himself - previously having made sure of the paternity. It was confirmed, and the kid will grow with the father who, however, should pass a number of judicial instances for confirmation of the rights. And young parents of the nice two-year-old baby did not doubt at all the one who her father: doubted - and publicly - the grandmother (she is a mother-in-law). It is necessary to hope that the DNA protocol - researches put an end family conflicts.Diagnostics of paternity is more often carried out by
for children (including not been born yet), but is frequent also for adults. Here a case from practice: very elderly childless spouses thought of the one to whom will remain acquired. The husband remembered old “sin“: it seems, then the daughter was born... They found for already elderly woman too, and examination confirmed paternity what the wife, seemingly, was delighted even more husband to. They do not wait for the help, but who knows - can be, between new relatives there will be relations which will brighten up life of old men.
Now about posthumous examination. Recently it was written about the Frenchwoman considering herself as Yves`s daughter Montana and demanding exhumation of his body for carrying out genetic examination. However sometimes posthumous examination can have other reasons and be carried out differently. For example, couple was not married and till the child`s birth the father died. If his parents or other close relatives agree to take part in examination (and news that the dead had child is frequent though somehow softens their grief), it can be carried out practically with the same reliability. In case of participation in examination of only one of parents of the dead or other same-gender relatives its carrying out depends also on a sex of the child as in such cases “man`s“ DNA - the markers (which are on Y - a chromosome and available only for men have special value). It is in certain cases more important to investigate the markers which are inherited only from women (they are in DNA of mitochondrions - special non-nuclear formations of a cage which are absent in man`s gametes).As we see
, genetic definition of relationship can help with very many situations. By the way, the plot about diagnostics of paternity appeared also in our TV series “Family secrets“: the expert bribed by mercenary relatives draws the false conclusion. It is absolutely excluded, and matter not only in moral qualities of experts: it is very easy to recheck the analysis which data are absolutely invariable, and not only loss of professional reputation, but also criminal liability will be payment for forgery.the Reality and conjectures
Sometimes to us ask
such questions: whether perhaps “mixed“ paternity if during conception the woman had not one sexual partner and whether the genotype not of the father, and other partner of mother, including old can affect the child`s genotype (and, respectively, results of diagnostics of paternity). The answer is unambiguous: no.
Sometimes the superficial knowledge of these or those questions of genetics is worse than ignorance, it can generate unreasonable fears and acts. There is an example: the father and the daughter - the student never addressed for confirmation of paternity, before not raising doubts. Shortly before it the girl for the first time learned the blood type, and it turned out that this group does not coincide with parental whereas the brother has a blood type of one of parents. Knowing that blood types are inherited, but without understanding how there is an inheritance, she considered herself as the nonnative child. Though family “deal“ of blood types was absolutely correct that to it and was explained, the girl insisted on research DNA, and misunderstanding was eliminated. Sometimes the unreasonable doubt in paternity arises in the presence at the child of the hereditary sign or a disease which is not found in families of both parents. Again - similar situations (which genetic reasons happen different) are absolutely natural. Especially it belongs just to an external dissimilarity what there was already a speech about.As we see
, questions of biological relationship and genetic examination are quite difficult (and in each separate case there can be additional problems which we did not concern here). Therefore the people addressing for examination of relationship talk to the doctor - the geneticist and before carrying out examination, and when receiving its results.
I the last: making the decision on examination of relationship, once again think whether really it is necessary for you.