I is the X that wrenched the Y's arm off and beat an arm and a leg off the X? Actually, it's Xi, not XI, so it's obviously a homozygous pairing of dominant and recessive. Actually, maybe it's Xi-X, rather than X-X? I don't know the term, but some aspects are linked with the X or the Y; in Katherine Kurtz' Deryni novels, the Deryni gene is X-linked. A homozygous Deryni is XX', a heterozygous Deryni is X'X'.

And here I was thinking that, as Xi, I was sumfin speshul. :)