His maternal grandfather, Yves Ourta (1912–1989), achieved eminence as a commander of the French Republican Guard and co-director of the National Gendarmerie.

Geisser's public profile was raised in 2009 when he became involved in a dispute with Joseph Illand, a senior engineer at the CNRS.

The matter became acrimonious and was picked up by the media,[4] promoted in at least one headline to the status of a Grand Affair ("l'Affaire Geisser").

[7] Meanwhile, Geisser found himself called before a disciplinary council by the CRNS under circumstances which according to one side in the debate threatened his right to free speech.

[9] He is also much involved in public life in his home city by adoption, Marseilles, where he participates in numerous debates on the theme of "living together".