Roger de Ponthieu - He Married His Grandmother?

Curt Quentin Harris do you have a copy of the marriage certificate?

Was Roger +18 when he married his grandmother?

I did have a quick look and found http://fmg.ac/Projects/MedLands/nfraamp.htm#_Toc494871036

The first few generations match the structure found on Geni starting from Roger's grandfather Helgaud de Montreuil, I except that the dates are all wrong and as usual most of the wive's names are unsupported (which readily explains how Nana Berthe could get confused with Madame Berthe).

The documents recorded at Medlands aren't particularly conclusive, unfortunately Geni tends to make everything look very clear cut when really in this era it's conjecture and supposition a lot of the time.

I don't see any evidence that Berthe De Ponthieu de Boulogne was a granddaughter of Charlemagne's.

Perhaps Private User can clarify.