Twin genetics depend on what kind of twins we are talking about. Having identical twins is not genetic. On the other hand, fraternal twins ...TheTechInteractiveShareAHandyGuidetoAncestryandRelationshipDNATestsClickheretoorderourlatestbook,AHandyGuidetoAncestryandRelationshipDNATestsTwinsBacktoTwinsMysonisgoingtohavetwins.I'mafraternaltwinandIhaveanotherbrotherandsisterthatarefraternaltwins.Myhusbandhasonhissideofthefamilytwins(fraternal)andtriplets-boys.Isoursonhavingtwinsbecauseofourbackground?Doesithavetodowithourgenetics?-AcuriousadultJune25,2014Thatisaveryinterestingquestion!Andonethatmanypeoplewonderabout.Infact,weansweredaverysimilarquestionmanyyearsago.Twingeneticsdependonwhatkindoftwinswearetalkingabout.Havingidenticaltwinsisnotgenetic.Ontheotherhand,fraternaltwinscanruninfamilies.Geneticscandefinitelyplayaroleinhavingfraternaltwins.Forexample,awomanthathasasiblingthatisafraternaltwinis2.5timesmorelikelytohavetwinsthanaverage!However,foragivenpregnancy,onlythemother’sgeneticsmatter.Fraternaltwinshappenwhentwoeggsaresimultaneouslyfertilizedinsteadofjustone.Afather’sgenescan’tmakeawomanreleasetwoeggs.Itsoundslikefraternaltwinsdoindeedruninyourfamily!But,sinceyoursonisthefather,hisgenesareonthewrongsideofthefamilytree.So,yourfamilyhistorylikelydidn’tplayaroleinhiswife’stwinpregnancy.Theanswerwouldbedifferentifyouwereaskingaboutadaughter.Also,althoughyourson’sfamilyhistoryoftwinscan’tincreasehiswife’schanceofhavingtwins,hecanpassthosegenesdowntoyourgranddaughter.Withyourstrongfamilyhistoryoffraternaltwins,thisjustmightincreasethechancesofyourgranddaughterhavingtwins!But,yourdaughter-in-lawisnotnecessarilyhavingtwinsbecauseofhergenetics.Otherthingslikeenvironment,nutrition,age,andweighthavealsobeenlinkedtohavingtwinsaswell. Andthereisalwayssimplechance…everywomanhasachanceathavingfraternaltwins. Itisjustthatsomewomenhaveahigherorlowerchance.Huh?HelpMeUnderstandtheGenetics!Waitaminute.Onetypeoftwinshasageneticbasisandtheotherdoesnot?And,onlythemom’sgeneticsmatter?