For babies not to develop problems they can only interbreed one generation which would be the mother and father of the 15 babies. I interbreed ine generation and the babies were smart and they had huge wings I measured and the males wings were five feet! And females were 4 1/2 and they can fly like no bodies business, but if u interbreed tht generation te babies will become retarted and either due at birth or you have the burden of them acting like babies all their lives but have raging hormones and pretty much do it with anything , like I accidentally inbred the already inbred generation and I had a baby boy hatch and he isn't really righ and he'll "attack" you during mating season
But I adde muscovies to my flock last summer and I got another male for Christmas so it worked out. Also inbreeding mainly affects male babies because they have two of the same same chromosomes ( ex. XX). And females are the ones with the different ones they have XXY and because of the y the females decide the gender of the babies , and also because of the Y it cancels the retardation
But agin if u only interbreed one generation ur fine
