As you can see, not all scientists are politically controlled (yet), so please do enjoy this video in French, based on an Icelandic study:
An English source stating similar things: https://en.wikipedia.org/wiki/Outbreeding_depression
The actual study (in English): http://www.d.umn.edu/~jetterso/documents/Helgasonetal.2008.pdf
A brief summary in English: it’s not good for us.
