Always only one chick hatches!

[Victoriaelizibeth]

So I am just wondering if this happens to anyone else ever? I have had four hatches from 3 different broody hens this year, and only 1 egg has hatched every time. Each time there has been more eggs that just don't hatch but when the broody finally hatches her one chick and abandons the remaining eggs I will candle them and there were definitely signs of chick growth, they just seemed to have died sometime before hatch. Does this ever happen to anyone else? Everyone else I know that has broody hens always end up with tons of chicks, and now out of four times only one chick each time just seems odd lol. Thanks!!! Picture is of the newest chick that just hatched yesterday.

 

[Skyle]

The chickie is so cute!
Anyways, how many eggs do you give to the broody? You have to be sure she can always cover well them all, or the eggs may get chilled and die. Do you put all the eggs under the broody in the same time?
Only another thing I could think about might be long-term consanguineity between rooster and hens, or some lethal genes in omozygosis (like short legs in seramas and japanese bantams or ear tufts in araucanas)