Can I use ground turkey instead of beef or pork?

I don't see any reason why you couldn't use ground turkey or chicken in place of the ground beef or pork. Some of the people in the remarks section of the recipe mentioned doing a vegetarian version, and one person used lamb. This is a family style dish, after all, and grandmas/moms all over the world will use what they have to make family favorite dishes like this. Sure, the flavor profile will be slightly different, but that won't make it wrong, or not taste good. So do what moms have always done- and use what you have, or what you feel is best for your family. Be that ground turkey, lentils, beef, pork or lamb - I'm sure it will taste good.