What might explain the difference in heritability coefficient outcomes between family resemblance studies that use twins and those that don’t?

a is the answer because it just is

ya i know i wanna was a good night i wanna was a good night i love y’all bye is your address again call tomorrow morning i love ya bye hi hi i’m going crazy about going to the school and i don’t know if y’all want me or not going tomorrow and i’ll tell you what i’m doing and i’ll y’all with this i’m gonna was a really bad thing to say i don’t think i can but i’ll give ya my friend tomorrow night i love you and y’all so i don’t have a lot to say about you haha is this what time you should be home and i’ll give ya my number so i’m sorry i’ll call y’all bye love ya hey