Prince du sang and French citizenship question?

I don't know who is Roger I.

Frank R.A.J. Maloney...

[deletion]

The Norman king of Sicily, perhaps?

pierre_aronax...

How and why would his descendents be princes of the blood?

Frank R.A.J. Maloney...

They wouldn't as far as I know but I ain't the guy what proposed the name.
I'm guessing the thinking went along the lines of he's Norman, so he's
French; he's a king, so he's royal. French plus royal equal prince du sang
in someone's mind. Possibly.

Not mine, I hasten to add.

pierre_aronax...

I see what you mean. In France "prince of the blood" means implicitly
"prince of the blood [of France]", in other words "in line to the
French throne". As a title, it means "in line to the throne and not
enjoying a higher title".

However, there were "princes of the blood of Navarre" in the 16th and
17th centuries, when the two crowns of France and Navarre were only in
personal union and some people where in line for one or the other crown
but not for both.

For the descendents of Louis III, the question is rather academic since
there are no living male line descendants of that king.

All princes of the blood are descending of King Hugh.

I'm a bit confused and could use some help.

Are currently living descendents of French kings considered Prince, or
Princes, du sang's and do they have French citizenship regardless of
birth country?

Also, would this apply to descendents of Edward III?

Thanks, in advance to everyone for your time.