In order to understand parental favoritism, let’s first look at these two hypothetical scenarios:
Jenny always felt that her parents favoured her younger sister over her. She knew it wasn’t due to the age factor since she was only a few months older than her sister. Also, she was more hardworking, studious, calm-tempered and helping than her younger sister.
It didn’t make sense that her parents doted more to her younger sister who barely had any good personality traits.
By the same token, Arun’s parents seemed to prefer his older brother but, on the contrary, it was pretty clear to him why. His elder brother was much more successful than him.
Arun would be frequently at the receiving end of his parents’ bashing, pestering him to take his career and life seriously. They compared him to his elder brother, saying things like, “Why can’t you be like him?” “You’re such a disgrace to our family.”
Origins of parental favoritism
Although many would like to believe otherwise, parental favoritism exists. The main reason being that parenting, in and of itself, is a costly affair.
Whenever we do something that incurs huge costs on us, we have to make sure that the benefits we gain outweigh them. Take the example of a firm. A firm will only decide to provide specialized costly training to its employees if it knows that it will bring more profits to the organization.
Spending a huge amount of money training employees who aren’t delivering is money going down the drain. There has to be a bigger return on investment for the big price paid.
Similarly, parents expect a return on their investment from their children. But there’s a catch- they primarily want in the form of reproductive success (successful passing of their genes to the next generation).
Speaking in terms of biology, offspring are basically the vehicles for parents’ genes. If offspring do what they’re supposed to do (pass on their parents’ genes) without hassles, then parents will benefit from their lifelong investment in their offspring.
So it makes sense that parents consider those kids who’re likely to contribute to the reproductive success of their genes as their favourite child and press those who’re not to change their ways so that their odds of reproductive success also increase.
Jenny’s younger sister (Scene 1) was more beautiful than her. So she was more likely to be reproductively successful than her, at least in the unconscious perception of her parents.
Jenny’s mom badgered her to visit salons and parlors to encourage her to improve her looks. Her mother hated the fact that Jenny didn’t maintain herself, and for good evolutionary reasons. (see What do men find attractive in women)
On the other hand, resources accrual is the key determinant of reproductive success in men and so, instead of pestering him to change his looks, Arun’s parents wanted him to take his career seriously. They favored their elder son because he was likely to yield a good reproductive return on their parental investment.
Why step-parents tend to be jerks
It is well-known that biological parents typically provide more love, care, and affection than substitute parents. A child raised by step-parents is at a greater risk of physical and emotional abuse.
As I mentioned before, parenting is costly. Not only in terms of the resources invested, but also in terms of time and energy devoted to raising children. It makes no evolutionary sense to raise offspring that do not carry your genes. If you invest in such offspring, you’re incurring unnecessary costs on yourself.
So to motivate stepparents to avoid investing in genetically unrelated children, evolution has programmed them to resent their step-children, and this resentment often rears its ugly head in ugly ways in the form physical and emotional abuse.
Of course, this doesn’t mean that all step parents are abusive, just that the chances of them being jerks are more; unless some other belief or need overrides this evolutionary tendency.
The mystery of adoption
Say a couple were unable to have kids on their own and decided to go for adoption. They loved and cared for their adopted child as much as its biological parents would. How does evolutionary theory explain this behaviour?
It depends on the unique case that one may be considering. But the simplest explanation could be that ‘our evolutionary behaviours are not fixed in stone’. A person can, in his lifetime, acquire beliefs that make him act opposite to what his evolutionary programming demands.
We contain multitudes. We’re a product of both our genetic programming and past life experiences. There are numerous forces battling it out in our psyche to produce a single behavioural output.
The important thing to remember, however, is that no matter what the behavior, the economic principle of costs v/s benefits still holds i.e. a person will only do a behavior if its perceived benefit outweighs its perceived cost.
It could be that the couple mentioned above, by adopting a child, is trying to save their relationship. Because the news of not being able to have kids can be distressing and a strain on the relationship, the couple can adopt and pretend that they have a child.
This not only saves the relationship but keeps alive the hope that if they keep trying, one day they might have kids of their own.
Since parenting is costly we’re programmed to enjoy it to offset the costs. Parents get a deep sense of satisfaction and contentment when they care for their young. It could be that parents who adopt are primarily satisfying this pre-programmed need for satisfaction and contentment.
Claiming that parents who adopt violate the principles of evolutionary theory is like claiming that having sex with contraceptives goes contradictory to the fact that sex has the biological function of passing on genes.
We, humans, are cognitively advanced enough to make the decision of hacking into that function to just go for the feeling part. In this case, pleasure.