China relaxed its so-called one-child policy this month, and everything from online opinion polls to piano stocks jumped for joy. The theory seemed to be that the only thing keeping Chinese couples from breeding more piano players was Communist party policy.

Of course, even in planned economies things are rarely so simple – especially when sex, money and tiger mums are involved. The policy change will allow couples to bear a second child if one of them is an only child; previously they both had to be singletons. It’s probably safe to assume that many of the babies born as a result will learn to play the piano. What’s riskier is assuming that there will be a baby boom in the first place.

Symbolically, emotionally and possibly politically, the policy change is a big deal. For most people most of the time, the party stays out of their private lives – except when it comes to procreation. The further Nanny steps away from the nursery, the more popular she will be.