How tall are they? When did they come up?

One thing I'd read, but didn't try when I did seedlings, is to have a fan blow gently over seedlings to help strengthen the stems.

Another thing I did do was start the lights really close (maybe 4-5 inches above the seedlings after they put out true leaves? Can't remember exactly), and then keep raising them up as the they grow. Kept from having them to struggle to get enough light and get leggy supposedly.

You might want to try pinching some of them back to see if that helps. Just leave on some leaves intact at the bottom.

HTH- Lisa

It may be that the stems are thin because they didn't get enough light and got leggy. You could try putting the lights really close to the tops and see if it encourages them to bush out. Were you planning on growing them outside? Not sure where you are in Texas, but be aware that peppers are completely frost intolerant, so you may not have a lot of time.