Do Adoptees think about Birthparents as much...?

That's the first question I've had on my mind the past little while. I've heard adoptees and others always asking and wanting to know if Birthparents remember or think about their birthchildren so what I want to know now is do adoptees think about their birthparents too? It's just with thinking and wondering about my birth nephew that will be turning 21 next week - I find myself wondering, does he think or wonder about his birthmother (my sister) or his birth family (my family) etc. or does he not think about my sister or her family? I just wonder how often do adoptees think about their birthparents or biological family/relatives, i.e., grandparents, aunts, uncles and so on. Well and I also wonder as my girls grow up will they think of me very much or not very much since we have contact through letters, pictures, home movies and so forth. Will my girls want a relationship with me when I'm older or will they just want to meet me to thank me and that's it and they move on with their life. We talk about fear of rejection all the time, but it seems sometimes that I hear more about fear of rejection from adoptees, but I know that I fear rejection from my girls when they're older sometimes. I think fear of rejection is just common all across the board with the adoption triad. So, that's my question is do adoptees think about birthparents and/or biological family/relatives?