Genealogy: Cloning Naturally Or Family Genetics?

     Have you ever noticed in certain family lines, it's like they've been cloned.  At certain ages, it's hard to tell who is who.  See what I mean in the following pictures:

William P. (Arville's father) & Martha Harper (Arville's mom)

Arminda (Arville's step-mom) and William P. Harper (Arville's dad)

Arville & Manila Harper

Clifford, Arville, Bernum & Erchel Harper 

Clifford and Erschel Harper

My nephews (my brother's boys)

My other nephews

My Dad

My brother 

My grandson

Me 3 months

My daughter, JB, 3 months

Granddaughter 3-6 months

Me

daughter

granddaughter

My Mom

Me

My grandmother Manila Harper

My great niece 

My Dad's Sister

My sister

Does make you wonder doesn't it?  I bet my g-g-grandfather looked just like my Dad, Granddad Arville and G-Granddad William. I know my Mom's sister and Mother could have been twins. What about your family, anyone look like an ancestor?