Being 27 and single isn't a big deal for most young women, though it is a huge deal if you're a Duggar. Jana Duggar and her twin brother, John David, seem to have been skipped over by Cupid's Arrow, as the pair continue to watch their younger siblings marry and have children.

While fans speculate often about John David's life, it is Jana that people wonder about the most. The 27-year-old constantly single Duggar daughter still lives at home, and most people assume that she acts as care-taker to her younger siblings that still live in the house, in addition to helping with her sister-in-law, Anna Duggar's five children.

However, fan have several theories as to why she is still living at home.

She's the live-in babysitter

According to the Tumblr, Duggar Bates Confessions, Jana is still living at home because one of the girls was appointed or volunteered to continue to raise the children for their mother, Michelle. In the early years of "19 Kids and Counting," when Michelle was still having children, she made it very clear that her job was to have a baby once a year or once every two years. During that time, she would be the child's "buddy" and would take care of the infant's needs.

Once the children got older, they were passed on to an older sibling who acted as the child's caretaker. It was even rumored for a while that Jessa Duggar Seewald was teaching most of the children their homeschool curriculum, despite the fact that she isn't a qualified teacher.

Some think that Michelle doesn't know how to care for children who aren't babies, so she has trapped Jana into living at home for as long as possible to ensure she always has an extra pair of hands to help out around the house.

She's waiting for John-David

One rumor and fan theory is that Jana is waiting for her twin, John-David to tie the knot first.

In a Reddit "Ask Me Anything," someone who claimed to be close to the Duggars claimed that Jim Bob Duggar, the twins' father, wanted the pair to have a double wedding, which would be a hit for ratings. However, this is totally unsubstantiated.

However, John-David may actually not have an interest in getting married at all. It has been rumored he is courting a woman in another state, but nothing so far has come of the rumor.

Instead, John-David has often joked about being a "bachelor until the rapture," meaning if Jim Bob is waiting on a double wedding, it might be a very, very long time.

Sound off in the comments — why do you think Jana is still at home?