Family troupes are familiar in music. Dance in the 20th century has been overwhelmed by the cult of agelessness and sex appeal. Setting its course against this tide since 1975 has been NdiBem, a family dance theater company that performed at Glen Echo Park yesterday afternoon.

Necessity was the reason for founding the group, according to Idrissa Gibbs Wilson. She is a mother who had to take care of her children but also wanted to dance. The current roster consists of three girls, three boys and two women, Wilson and Amelie Oubree.

The children speak clearly in skits based on animal fables. For dances that use work and prayer motions, their timing and spacing are precise. As a group of pupils they exude charm, but individual talent seems to have been drilled out of them.

Wilson is intense, dedicated. She paced like a lioness. Most of her dancing was an elaboration of what the children did, though she did indulge in one passage that called for arabesques and leaps. Oubree projected a softer image in a jazzy dance in which hips and arms were prominent.

NdiBem's material is based on African and Afro-American sources. It is simply but meticulously costumed and staged.