Gene strands are used for purchasing upgrades that provide various bonuses. Gene Strands and Gene Strand upgrades are not lost after attacking a planet.
Unspent Gene Strands provide a 1% increase to global BPS.
This can be increased to 2% by researching Schroedinger's Gene at the Dark Matter Institute.
New Gene Strands can be obtained by killing a percentage of a planet's population.
When entering a Black Hole, Gene Strand upgrades are lost, but the unspent Gene Strands are transformed into Dark Matter.
Main page: Gene Strands