I hate to even post advice since I am quite the newbie myself, but you should probably start by thinning them down to just one or two plants in that pot. My understanding from what I've read elsewhere on this site is that if you are careful, you could even transplant the ones you pluck into their own pots. I'm jealous, my 5 week old plants are only seedlings with 2 tiny leaves.

What type of light are you using? To me, they look as if they're too "leggy" the term when the stem gets tall, but weak as the plant tries to find more light. Sweet basil leaves like this are very heavy, and it looks as if the stems aren't strong enough to hold them up. Also, some type of airflow, such as a fan (or wind outside), also encourages stems to strengthen, though I'm not sure it would work for these at this point.

I also agree with the last poster--probably 4 stems for this pot size. Basil seedlings generally tolerate separating better than a lot of plants. I'm not familiar enough with transplanting to know if you can bury part of a basil stem in order to get some more stability.