From their Viking ancestry, haplogroups I1, I2b, R1a1a and R1b1b2 (mostly U106). But the same is true of previous Anglo-Saxon and Danish invaders to Britain, as they shared the same region of origin in Denmark and Frisia.
But the Normans were already well mixed with the native Gallic French, who were predominantly R1b (mostly L21 with some U152 and M167) with I2, J2, G2a, E1b1b and T.
Because north-west France has so much R1b-L21 like ancient Britain and Ireland, it is very hard to tell which is of British or Gallic origin. The linguistic link between Britanny and Wales suggests that Roman-era Britain and north-west Gaul were quite close, so it's not surprising to find the same dominant haplogroup.