For couples, the secret to happiness is kids, but only if parents are married, say researcher.
According to Dr Luis Angeles, of the University of Glasgow, raising children has little or no positive effect for unmarried couples, reports The Daily Express.
However, in case of married individuals, children increase life satisfaction.
Dr Angeles' study has been published online in Springer's Journal of Happiness Studies.
He pointed out that, in the study, when asked about the most important things in their lives, most people placed children near or at the top of their list.
Dr Angeles said: "One is tempted to advance that children make people better off under the 'right conditions' - a time in life when people feel that they are ready, or at least willing, to enter parenthood.
"This time can come at very different moments for different individuals, but a likely signal of its approach may well be the act of marriage."