It was during their Full House days that little Mary-Kate and Ashley Olsen met Sister, Sister ’s Tia and Tamera Mowry.

Mary-Kate Olsen—who, along with twin sister Ashley Olsen—prefers to stay out of the public eye, stepped out for a casual ...

'Full House' Star Says Mary-Kate and Ashley Olsen Not Returning for 'Fuller House' was a 'Missed Opportunity' originally ...

Ashley Olsen rose to fame alongside twin sister Mary-Kate Olsen with roles in Full House, Passport to Paris, New York Minute ...

Tia Mowry recalled visiting the 'Full House' set with twin sister Tamera and babysitting stars Mary-Kate and Ashley Olsen: ...

Mary-Kate Olsen was spotted out in the Hamptons, looking casual in an oversized tee and sweatpants while at a local farm on ...

Mary-Kate and Ashley Olsen had famous babysitters while on set of Full House. Fellow twins, Tia and Tamera Mowry, watched ...

Mary-Kate Olsen traded her high feels for flip-flops in a recent rare outing. Olsen, 39, was photographed out in nature while ...

In celebration of the sisters' 39th birthday, here's a look back at at some of their cutest lookalike moments from years past ...