If having ovarian cancer is normal, then why can't those women get pregnant?

Firstly, you're confusing 'normal' with 'natural'.

A 'normal trait' (such as heterosexuality) is, by defition, something that is common to the majority of people.

A 'natural trait' (such as homosexuality, or, for that matter, ovarian cancer) is something that occurs naturally without external intervention.

Some things are both normal and natural, even if they are considered afflications, like losing your eyesight with age or having grey hair.

Homosexuality is, as has been discussed so very, very often (and yet some people still seem to ignore this fact) natural. It occurs in populations of almost every mammal, as well as other animal groups.

You can consider it a disease or an abnormality or whatever, and I guess you'd be right.

I'm always amused by the argument that being gay is a product of your environment or your upbringing or something. Has no one ever wondered why mothers don't have whole families of gay children? Logically you would expect this to be the case, since each child has been raised in the same environment.