Yes, I'm sure you're quite capable of doing the research on your own. However, here are some talking points you might wish to bring up:

-Get some information about CB1 and CB2 receptors in the brain and compare pharmacological processes behind cannabis and alcohol. Alcohol functions much differently, and far more dangerously.

-Look up the addictive properties of cannabis, tobacco, and alcohol. Tobacco should be obvious - yet to your parents, similar facts about cannabis might not be so clear. Alcohol as well. It's addictive poperties operate in a way very similar to those of heroin.

-Perhaps most obvious, just look up general death as a reult of overdose statistics. Alcohol is 20,000 annually, with another 100,000 if you include traffic accidents and long-term effects. Tobacco is somewhere in the 400,000s (all due to long term use). Cannabis is currently at 0 in terms of overdose. However, while long term effects are mostly unknown, it is suspected to be mostly harmless. Show them studies which show no link between cannabis and lung cancer. I know there are also a few out there about how cannabis can help PREVENT the growth of tumors as well as heart disease.

Also, be able to provide sources to your parents. This should score major points with any reasonable adult. You have researched your drug of choice, know how to use it safely, and know the effects it will have on you. Unfortunately, when it comes to drugs, parents tend to lose their sense of reasonableness.

Good luck.