And it was reported on the BBC a couple of days ago too.
Really? Babies suckling milk is surely instinctive? As well as being revolted by things that taste bitter. Humans have lots of instincts. I certainly didn't learn those things through observation.
Babies have to learn to suckle. If they are not taught, they cannot latch on properly. It is one of the main reasons that women think they cannot breast feed since, of course, the suckling has to be learned by the mother as well.
As for bitter tasting things, they are probably regarded as 'revolting' because our taste buds have been trained by the easy availability of sweetness in the modern world. Our tastes in food are trained from the moment we are born - sooner, maybe, since there is some evidence that tastes are formed in the womb, from what the mother eats. Food plants prior to intensive breeding were much more bitter - as can be still seen from foraged plants. Apparently, the bitterness starts our digestive juices working.