What kind of creature always gives birth to same sex twins?

Certain species of reptiles, such as some types of lizards, are known to give birth to same-sex twins. This phenomenon can occur due to environmental factors or genetic predispositions that influence sex determination. Additionally, some studies have indicated that certain mammals might also exhibit this trait under specific conditions, but it is less common. Overall, the occurrence of same-sex twins is more frequently observed in reptiles.