Answer: For decreased chances of rejection
Explanation:
The three higly polymorphic MHC 1 genes in human beings are HLA-A, HLA-B and HLA-C.
These determine the compatibility of the organ or tissue in the recipient's body each by the help of many alleles that segregates in a population.
There are very less chances that a random chosen donor will match the a recipient six allele genotype.
This is the reason parent may be the best donor for organ transplantation or tissue transplantation.
