Casting the Twins
Like many family shows, there were twin characters, in this case, Sam and David Camden. The twins were the youngest of the Camden children, and they were born during the third season of the show. Many TV programs will have multiple actors playing the parts of twins as there are a lot of legal issues to consider. And the same was true in the case of Sam and David.
Originally they were played by quadruplets Lorenzo, Myrinda, Nikolas, and Zachary Brino, in order to get around child labor laws. But, as the siblings began to age there were noticeable differences between them, so the official actors were cut down to Lorenzo and Nikolas. The pair has not carried on acting since the show ended, and count 7th Heaven as their only acting credits.
