When using ‘positioned’ hair, like on faces for instance, it is usually better to avoid interpolated children; one hair left of an eye and one to the right gives interpolated hairs in the eye! Simple children can be ok!
Interpolated children can be used for something like a continuous field of grass or a carpet…
When used for eyebrows or so, use a separate particle system for each one, when you want to use interpolated children.
