I know a lot of Egyptians seem to identify as "Arabs" but I'm not sure if that really goes much beyond sharing a same language (and influence by Arab nationalist leaders such as Abdelnasser).
But are Egyptians actually (genetically I guess, or however else you measure it) Arab? Don't they have more in common with other African nations or are they unrelated to either and have their own Ancient Egyptian heritage?
Egypt has been invaded by quite a number of countries so obviously they share a mix of each but if someone has any statistics I would appreciate that =)
I am not knowledgeable enough to answer your question, I will just point out that this question is still very loaded politically as claiming any sort of paternity of the "Egyptian civilisation " can be a powerful tool to define identity and legitimacy.
If you want an example of this, you can look at the controversies surrounding Cheikh Anta Diop theories.
Note: once again, I am not qualified to take any position, just pointing out that you are entering a loaded territory.