This is again information on DNA from the Wells surname group 11:38 AM 8/26/2005, Lady Bonita \(USA\) wrote: >1) the father passes some markers to the daughter, but the daughter DOES >NOT pass them on to her children. Thus, they can check for paternity of a >child with both parents DNA. Well, not quite true. The father will pass NONE of the y-chromosome DNA to daughters. They DO get his X chromosome (passed to him by his parents). This mixes with the X chromosome passed by the mother to form a full X (mixed in some way). All other chromosomes are passed pretty much 50% from the father and 50% from the mother. These ARE passed on to the next generation but diluted by 50% (more or less) to mix with the genetic matter from the other parent. >2) The same happens with the mother ... she does pass some markers to her >son, but the son DOES NOT pass those to his children. As above except for the mtDNA that is passed from the mother to BOTH daughters and sons. None of the mtDNA from the father (except in very rare situations) is passed to the children. Only the daughters then pass this on to later generations. The 50% rule applies to all other chromosomes passed on by the mother. None of the chromosomes other than the y are currently being tested for genealogical purposes. But this 50% mixture is a great help in paternity testing provided they have something to compare against. Two siblings will have enough DNA in common from the two parents that they can be declared siblings to a high confidence rate even without a contribution from the parents or other close relatives. But there is a higher confidence level if other family members are available for testing.