odd sex ratio in hairless rats?

[StillBP]

Ok
so a wile ago I was at the small, locally owned pet store i sell some of my pet quality snakes at, and buy some feeders form,and he had hairless rats he took in on trade that he was selling for feeder price.
Now I only give $2.50 for a feeder from him due to the fact i sell, on consignment, snakes there so he gives me a break in price add that to the fact that i spend $40 or $50 a week in feeders there.
Anyhow I bought the only female he had to toss in to my breeding group. Now i hadn't heard that some lines of hairless have lactating issues, I got lucky that she has never had any issue feeding her babies. but back to my story, I have produced from her maybe ten total litters, she always has rather small litters 3-5 but has big fat healthy babies, and in total has only produced one female in ten litters(at least 35 babies most likely 40)
now my male that she has always been breed to has never had any issues throwing females with any other rats he breeds so it is not him.
my real reason for questioning the sex ratio is her daughter just had 9 babies ,het male from het hairless's first litter to het female out of a different litter (sadly only got one hairless out of 9) and all 9 are male

so my question is have I just been unlucky in sex ratio or is there something screwy with hairless that does this?
also would like to add that the hairless is now retired and no longer breeding stock for me. I replaced her with her het daughter when she had a larger litter as 3-5 babies will not help feed my snakes (that and I do not feed my hairless they go to pet homes)

[wolfy-hound]

My hairless produce both males and females fairly regularly.

[StillBP]

figured the gene gods were just messing with me but ya know had to ask