翻译英语"从这点来判断，你不是一个好哥哥，或者说你没有尽到一个哥哥的义务，因为你连妹妹的年龄都不知道

Judging fron this, you are not a competent elder brother. In other words, you have not take the responsibility of being an elder brother, because you even do not know your younger sister's age.

Judged by this, you're not a good brother, or you haven't done a brother's duty because you even don't know your sister's age.

From this point to judge,you are not good brother or you do not have the obligation to a brother for you don't know your sister's age.

From this point to judge, you are not a good brother, or you do not have the obligation to a brother, because you do not even know her age