In real life nature, there are instances of something called Sexual Dimorphism, a phenominon in wich males of a species will have some traits, and females will have others.
Common examples would be male Deer having large antlers, while females have none, Male Peacocks having bright, vibrant colours and large tails while the hens are small and bland, and the angler-fish, in which the female is large, intimidating, and possesses the trademark lure, while the male is little more then a minnow who attaches himself to her body.
Personally i would love to be able to see something simmilar (perhaps not as extreme as the anglerfish) in Niche, the ability to set say, Antlers to be availible only for males, while nimble fingers would be only for females.
Not exactly sure how it would work, especially if you do something like set big-body to be for males, and you get a male who only has recessive big-body genes or double lean-body genes. it might override it like how melanism overrides colors and patterns. but ideally there should be a way to select a creature and perhaps set up something similar to the mutation menu where you can set a specific gene for each sex, if that creature has an offspring born with that gene and they possess the correct sex, they will express it. if they are the wrong sex, they will not express it, but still carry the gene for any offspring they may have on their own.
i'm sure it could be done, and i'd love to see it myself. thank you for your time.