The article strikes me as being of the sort that is likely to be an exceptionally poor summary of the real research.
What on earth do they mean by teaching? Everything you do with your child is teaching it something. If they mean by teaching, parents' attempts to spoil a bit of fun by, eg, making a song serious, stopping their child to correct them and making them repeat it, then of course it's not going to benefit them. But enjoying singing a song with your child is not active teaching, it's interacting. Children who are not interacted with or who are only interacted with to suit their parents' higher agenda are obviously not going to do as well as children who are played with and talked to because it is simply fun to do that. And as for counting and reading - are they suggesting you actively avoid mentioning numbers to your child, sharing a book with him, putting together an alphabet puzzle with him, or pointing out the numbers on doors as you walk past????? Maybe better educated and therefore probably wealthier parents, just enjoy the process of passing on information a bit more than less well educated parents, so can do it in a more inspiring and confident way. I certainly know that I don't enjoy being read stories by people who can't read very well themselves and who don't honestly enjoy reading out loud (nor do I enjoy being sung to quite so much if the singer is tuneless and keeps forgetting the words...). Stories have to be made exciting and brought to life to inspire interest and therefore enhance learning.
Another thing that intensely irritates me about articles like this is the way all children are lumped together into a set of boring and utterly unhelpful statistics. Some children have no interest in counting, reading, writing, etc, etc, until quite late on, whereas others do. You can't force them to change their general pattern of development, so won't hugely benefit an uninterested child if you sit him down to teach him the alphabet when he wants to empty out the drawers in your bedroom, draw on the carpet with your lipstick and put your knickers on his head in order to make you laugh rather than tell him off (ie learn good social skills and develop a good sense of perception). But if you have a child who gets more excitement out of being read to, joining in and trying to read the words himself, than banging saucepans in the kitchen, then you shouldn't force him to bang saucepans all morning instead, because some twit in a very poor newspaper article said that research shows that "teaching" your child at a young age is not going to do him any good, without going on to analyse in any way what "teaching" means. If you are responsive to your child's genuine interests and share your own passions with your child, then you are never going to be doing anything wrong and are unbelievably unlikely not to be benefiting them. You can't force all children into the same box, though, which is what generalised statistics (and government policies) try to do.