Answer:
Re-producing sexually will allow the sea anemones to give their offspring a more diverse gene pool and can mitigate the risks of a genetic disorder being spread to the offspring because the bad gene has a higher chance become recessive if the gene of the anemone it mates with is more dominant (meaning it wouldn't allow the "bad" gene to show in the offspring) whereas otherwise, the offspring would have the same issues the mother did (assuming it had a bad gene to begin with).
