Match child on x-chrom, NOT parents

[yangorwhat]

Can anyone explain why someone (male) could match a child (female) on the X-chromosome (~8cM) but matches 0 cM on the x-chroms of said child's parents. Child matches each parent 100%, as would be expected.
I used gedmatch to do x-chrom comparisons.
Thanks!

Kim

[prairielad]

This is due to algorithm finding a match (more then likely false) by combining the values of daughters maternal x and paternal x.

two strings of letters(bases A,C,T and G), that in a mix and match combination, happen to match up with male in questions single string of letters.