Mary-Kate ja Ashley Olsen, samuti hästi tuntud kui Olsen'i kaksikud, sündisid 13. Juunil, 1986. aastal Sherman Oaks'is, Kalifornias, uhketele vanematele Jarnette'le (Jarnie) ja David Olsen'ile. Järeltulijad Olsen'i majapidamises koosnevad veel vanemast vennast Trentist ja nooremast õest Elizabethist (Lizzie), kes mõlemad on olnud külalis näitlejad mitmes kaksikute videos. Nende vanemad lahutasid 1996. aasta Märtsis ja nende isa abiellus MacKenzie Tayloriga, seejuures saades tüdrukutele kasuema ja noorema kasuvenna ja õe. Kuigi nende vanemad on lahutatud, nad jätkavad Mary-Kate'i ja Ashley professionaalse karjääri juhendamist koos.

Mary-Kate and Ashley Olsen, also famously known as the Olsen Twins, were born on June 13, 1986 in Sherman Oaks, in California, to proud parents Jarnette (Jarnie) and David Olsen.Siblings in the Olsen household include older brother Trent and younger sister Elizabeth (Lizzie), who both guest-starred in several of the twins' videos. Their parents divorced in March of 1996 and their father married MacKenzie Taylor, earning the girls a stepmom and two younger stepbrother and sister. Although their parents are separated, they continue to supervise the Mary-Kate and Ashley's professional careers together.

Best known for sharing the role of Michelle Tanner in the hit comedy series "Full House" since the tender age of nine-months old, Mary-Kate and Ashley have literally grown up before the public's eye. At the small age of only six-months, their mom, at the encouragement of friends, took them to an audition for "Full House". Babies after babies were allowed to crawl on the floor for the producers, but there was really no competition. They came in with big blue eyes and did not cry or fuss. On their very first audition, they landed the starring role. At this moment, their careers took off.

Over the seasons Full House was on air, Michelle had been growing up on the show,just as the girls had been growing up off-screen. America have witnessed such heartwarming milestones such as learning to walk and talk, heading off to the first day of school, mastering the two-wheel bike, and making the transition from a crib to a "big-girl" bed. On TVQ ratings which rank all the actors from best-liked to least-liked, Mary-Kate and Ashley are often rated number one in the girls popularity. In fact, they had become so popular that a talking Michelle Doll was modeled after them in 1991.

When "Full House" aired its final episode and said goodbye to the audiences in 1994, many people thought their careers had ended. After "Full House" ended, it gave the the girls more time and opportunity to work on bigger projects such as movies, music albums, and two hot-selling home video series, "The Adventures of Mary-Kate & Ashley" and "You're invited to Mary-Kate & Ashley's". Aside from these, they also have several book series which releases a new book every month, another mega-success area. They have formed their own production company, Dualstar, making them the youngest producers in Hollywood. They even have their own Barbie figurine dolls shaped after them. Talk about success!

Even with their busy schedule, they still must attend school. On days they are working, there is a tutor to help them with school work at least three hours a day. While they are not working, they attend a private school near home.

Though they are always seen together during press conference functions and movies, they go their different ways during their spare time. Mary-Kate is a devoted horseback rider, while Ashley is into dance. They almost never dress alike unless it is for business functions.