Do all mexicans with spanish last names, have spanish descent?

Question

My moms side is really dark skinned mexicans but they have Spanish last name. Its Sanchez...its a common last name in Spain does it mean they have spanish ancestry? They show no signs of spanish ancestry...they are really dark skinned with really dark hair and have dark brown eyes...no european traces whatsoever.

Answer 1

There is a possibility that your ancestors adopted a Spanish last name when they were not Spanish themselves.  

1. Oftentimes, landowners would "give" their last name to the people that worked their land.

2. Native Americans  would also just take a last name that they liked or that suited them.

3. A last name could have been conferred upon them at baptism to signal becoming "civilized"

Answer 2

i should think  all Mexicans have Spanish last names Mexicans are of mostly of Spanish ancestry the Spaniards would have intermarried with the indigenous people of Mexico Mexicans are mixture of Spanish Mestizo American Indian European and Mixed European Ancestry

Answer 3

Sure. The name persists even though there probably remains very little of Spanish DNA.Don't forget there were relatively few Spaniards, so the intermarrying in the years made us mostly dark again.

Answer 4

20% of the Mexican population is 100% European/Spanish. 10-15% is pure Amerindian. The rest are mixture of the two. Simply check wikipedia on the demographics of Mexico.