People who felt their parents were overly controlling when they were young are less happy than their peers in their teens, 30s, 40s and even their 60s, a new study suggests.

And it's not an insignificant amount - researchers from the University College London compared the drop in mental wellbeing to the loss of a close friend or relative. 

The study tracked a group of more than 2,000 people born in 1946 all the way through to the present day, with the aim of finding out what impact parenting styles had on their wellbeing throughout their lives.

The kids who reported having caring parents ended up with the highest wellbeing scores, while those who said their mum or dad controlled them psychologically - by intruding on their privacy or stopping them from seeing their friends - scored lower on a range of happiness tests.

Although many studies have looked into how parenting affects the development of children, this is one of the first longitudinal studies to look into how parenting can affect happiness over a lifetime.

But - and this is a big but - so far the study only shows correlation, and doesn't provide any evidence that psychologically controlling parents directly impact the mental wellbeing of their kids.

There are also some glaring issues with the research - mainly the fact that participants were asked to recall what their parents were like when they were children decades later, at the age of 43. This introduces the possibility of recall bias, whereby unhappy people will be more likely to remember their childhoods as being less than ideal.

The researchers admit that more research is needed into how control can negatively impact children, but they explained that the results also tie into studies that show children who form secure bonds with their parents go on to have happier relationship later in life.

"Parents also give us stable base from which to explore the world while warmth and responsiveness has been shown to promote social and emotional development," lead researcher Mai Stafford told The Independent. "By contrast, psychological control can limit a child's independence and leave them less able to regulate their own behaviour."

The study defined psychological control as parents trying to make the child dependent on one or both of them, intruding in their privacy, and being unwilling to let them make their own decisions.

In contrast, parents that were behaviourally controlling, for example, not letting their kids get their own way all the time, didn't appear to negatively impact on their children later in life.

The study measured the participants' wellbeing at four stages in their life: between the ages of 13 and 15, at 36, 43, and finally when they were between 60 and 64. At each stage the measure of happiness was slightly different - for the teenagers, it was measured by their teachers; in the 30s and 40s, participants rated their own satisfaction with their life; and in the 60s two independent scales were used to measure happiness.

There are obviously some pretty big gaps in the study that will need to be followed up, but it's an interesting insight into some of the ways parenting can leave its mark on children. We'd like to see some more results before we come to any conclusions, but if nothing else, it's a timely reminder that we can all stand to let things go a little more.

The results have been published in the Journal of Positive Psychology.