Twin Foals?

I've actually had twin foals. well they technicly were't my horse's twins but they were brother and sister. Both the same age and both showed up on my lot. So I ended up having 3 baby horses. What I did was once it said my mare was pregnant I ******** houses for the whole time she was pregnant. Then I went back to that sim family after that certain time and there were 3 foals in my lot.