No? If you’re a cis straight person, you’re going to be attracted to people of the other gender. For most people, this is both attraction to the behaviour (attracted to femininity or masculinity respectively), and the attraction to the specific gentials.
If I was 100% in that cis straight guy box, then for a female trans person to meet those requirements, they’d have to be fairly indistingishable from a cis female. That’s very rare, for example most people would not have had a vaginoplasty. If I was to date a trans guy, then I’d personally be put off by the masculinity, even if they had the genitalia I was into.
Personally, I’m not 100% straight because I’m more flexibile with the genitalia, so long as they have that femininity. But I 100% understand why other people wouldn’t date a trans person because they’re trans, even if they were fine being friends with them. After all, I wouldn’t date a guy even though I’m fine being friends with them, that doesn’t make me homophobic.
Eh, even if you count it, it should half for each step removed from you, as the non-existant grandchild’s other parent will still have a child, just with someone else rather than with your child.
It’s like saying that killing someone 1000 years ago will also kill all their descendants, which is technically true. But most of the descendants will still live, just one different parent (grandparent, etc).