Fantasy Genetics of Half Humans

Well, if gender distribution mechanism for fantasy races is the same as for humans (or horses, or donkeys), then yes, it might affect offspring mildly.
[But see below - I will contradict this by "the chromosome analisys", if I may use these words for the following simple consideration.]

Let us consider genetics.

A normal male human has 22 pairs of non-gender chromosomes plus one X-chromosome and one Y-chromosome.

A normal female human has 22 pairs of non-gender chromosomes plus two X-chromosomes.

Again.
Boy is XY.
Girl is XX.

Genes in X and Y are not the same (I mean, of two gomological [maybe I use improper word here, I mean "those constituting a pair"]) chromosomes each one has a gene regulating, say "something". These genes are not identical, but they have the same function. But, genes in X and Y gender chromosomes (at least some of the genes) are totally different.

Now, let us define
Elf Girl is XX Orc Girl is xx
Elf Boy is XY Orc Boy is xy

Let us see what kinds of children they can have...

Elf Girl + Orc Boy can have

Girl Xx
Boy Xy

Elf Boy + Orc Girl can have

Girl Xx
Boy xY

Aha!
Now, baby girls will not be different* if parents are reversed.
But baby boys might have different genes, and they might be very different, but only if X and x or Y and y chromosomes were very different.

But we already agreed that D&D races are not species (and horses and donkeys are), so Xy and xY boys should not differ dramatically (that is, much more than two XY or xy boys.)

[Although interracial breeding may produce greater diversity due to greater inital diversity of genes... Nevermind, consider this unreadable runes...]

[*of course they will be, but not in the sense we discuss...]