I was born without pubic or underarm hair, I have eyebrows but they never grow long. The hair on my head is thick and lustrous - other body hair sparse. What causes this?
There are genetic patterns that each of us inherit associated with both our heritage and our ancestry. American Indians, like their Asian ancestors, have very little body or facial hair. Many Asians do not have pubic or under arm hair. We have transplanted many Asian women who want pubic hair, but it will grow like your head hair, a bit more curly, so you will have to cut it to keep it short.
For your eyebrows, it sounds like you have very short hair cycles there, which means that the eyebrow hair may only be there for a very short time when it falls out and eventually gets replaced by other hairs. When this happens, the length is usually very short and the growth rate is always slow in the eyebrow, possibly slower on you then in many other people of similar ethnic background.