We all know a thing or two about siblings. Only-children have always wanted one, while those that have them share tales of rivalry, unfair treatment, and a bond closer than any friend.

Everyone’s familiar with “middle-child-syndrome,” or declarations of the eldest being the most responsible while the youngest is the wild one.

When it comes to dating, the most difficult one is often the youngest sibling of any family. Why, you ask? Allow me to explain.

1. Youngest Siblings Have Mastered Manipulation.

As the baby of the family, the youngest sibling is often the favorite of the mother (no matter how she may insist she loves all of her children equally). This can lead to a blind eye turned to misbehavior, and the child growing up used to getting out of trouble with a bit of charm. This is often a habit taken well into adulthood.

2. They’re Likely To Have The Least Intelligence.

If it seems like the oldest is smarter than their younger siblings, recent studies show this is actually the case. As it starts with the eldest and declines through the birth-order, the youngest is dealt the short stick in that department.

3. They’re Usually (Overly) Sensitive.

As the mother’s favorite, this can often bring the ire from other siblings, causing constant conflict which can lead the youngest to become overly sensitive. The smallest insult can become far more than intended, and the youngest can even go so far as to overreact to an imagined slight. Defensiveness becomes a reflex response to conflict instead of constructive communication.

4. Boy, Are They Irresponsible.

As parents become less hands on in their childrearing, the rules are often slacked by the time the youngest comes around. While this can lead to greater creativity, it can also breed irresponsibility as the parents simply clean up after the child and help them out of trouble, instead of putting in the work to teach them better habits. As they become adults, they’re often faced with a confusing world where no one is around to clean up after them.

5. Get Ready For Perpetual Immaturity.

Studies show that children will do as they need to in order to curry their parents’ favor. For the youngest in the family, this means behaving as the baby of the family. This can not only stunt maturity development, but even encourage it’s delay as the parents reward the immature behavior, as it is viewed as “cute” instead of recognizing it as the stunted emotional growth that it is.