"My little sister likes to eat steamed pork dumplings."
It's quite annoying that Duolingo marks it wrong every time I omit "的" in sentences like this denoting the relationship between family members. I've reported quite a few sentences now.
Yep, same issue. They are way too rigid in both the Chinese and English grammar that they will accept, which I understand takes time but the 我/我的 issue should have been anticipated.
February 7, 2019: I entered my answer without 的 before 妹妹 and it was accepted.