If my dad and grandfather have had a melanoma, is there an increased chance that i'll get one?

Yes: Genetic factors, including some very high-risk genes, run in families parent-to-child. Rather than study you genetically to determine your risk, simply keep a VERY close eye on your skin, everywhere, frequently. If you've got somebody special, make this their job. If not, your physician is your best friend here. Catch them early before they're able to kill you. Best wishes.