for shorter guys, if you wanna self-comfort, you can always refer to historical figures who are height challenged. but let's face it, you are not preferred in the eyes of natural selection.
for younger guys, what's wrong with you? can't you find younger girls? why resort to find elder sister to look after you? Be a man!
Overall, it's just my personal preference, yes it's super biased, I apologize. After all, i am not looking for just marriage.