Starched Genes is a Perk Card in Fallout 76. This Perk has 2 ranks with increasing cost in Luck. To use this Perk Card your character has to be at least level 30. You will never mutate from rads and RadAway will never cure mutations.

How do you get the starched gene perk?

To use this perk card, one must be at least level 30. At max rank, one will never mutate from Rads and Radaway will never cure mutations. While Starched Genes prevents mutations, at rank two it effectively makes acquired mutations permanent by removing the chance of RadAway from curing any.

Can you get rid of rads without losing mutations?

Mutations are a new feature in Fallout 76. It removes about 25 rads (more or less based on your perks) without removing your mutation. Mutations seem to not override each other, but using rad away without starched genes can remove both simultaneously.