using x-match, how?

[Yonnie3]

two cousins, 1 boy one girl, they share an X-match.  Does this mean they are on mom's side or something else? 

Is this confusing mtDNA with the X chromosome?  Can somebody explain this so a non-Phd can understand it?

[Alexander.]

X chromosome is inherited from both parents for girls, and from mother only for boys. Girls are XX, boys are XY.

The X-chromosome for the boy came from his mother (he got a Y-chromosome from his father). The girl's X match could come from either of her parents, because she got an X from each parent.

Keep in mind that small X-matches are not very significant (could just match by chance). I would generally not pay much attention to X-matches under 20 cM long.

Alexander.

[Yonnie3]

so how would X-match affect cousins, male-female?  My female 4th cousin got X from my dad or from my mother? 

So I have an X, my female distant cousin has a matching X.  Does this imply (A, B or C) she is from my mother's side of family? 
A: Strongly
B: Weekly
C: Implies nothing, red herring, why is X-match used at all.

[Alexander.]

I would say that it is weakly suggestive that the match is on your mother's side, since it is a distant match.

Your female 4th cousin got X-DNA from both her mum and dad. The match could be on either side of her family.

What is the length of the matching segment?

X-match can be very useful with determining whether close matches are from the maternal or paternal side.

[Yonnie3]

it's ftdna, I can't find where it shows the x-match amount.  The dna matchlist says we have a x-match but the chromosome browser shows zip.

[LizzieL]

I've just got my FT DNA matches and wondered about the X match too. Three of the X matches I have identified are on my father's side. Two are from his mother's side (one from her father's line and one from her mother's line. The third match is from my father's father's mother's father's line.
So I can't fathom out how I can use it at all to help identify the unknown X matches.

[Craclyn]

Since an X-chromosome cannot be passed from father to son you can rule out some possibilities when you are looking for common ancestors. Any line for either you or your match that goes through two consecutive males can be eliminated from consideration.

[LizzieL]

Since an X-chromosome cannot be passed from father to son you can rule out some possibilities when you are looking for common ancestors. Any line for either you or your match that goes through two consecutive males can be eliminated from consideration.

That's what I thought, so my below relationship must be wrong somehow. The match is stronger than expected for a half 3rd cousin once removed. Maybe I have a second match with the person through a different line. They were all from a small village so intermarriage likely.

The third match is from my father's father's mother's father's line.