Never has been so much intelligent people in this planet. And the cause is that technology had improved a lot the means to feed and educate people. The average population of the planet can have an IQ of 40 or 50 points higher than people 100 years ago. According to Flynn Effect
The Flynn Effect And IQ
Then your question presents a false premise.
Technology had permitted to educate much better the middle and the lower classes of society, and this resulted in a general increase of intelligence. Basically because machines had liberated a lot of people of hard labor. In past centuries only aristocrats and rich parents could expend money to educate their children. Things had changed since the end of the IIWW.
In fact, the Flynn Effect had debunked the idea that intelligence is due to genetic factors.
The Flynn effect do not disprove intelligence is related to the intelligence of the parents. But this happens not for genetic reasons, but for educational ones. Intelligent people tend to teach their children to become intelligent as well. It is similar to mother language. Mums tend to teach their children their own language. And if they can speak some foreign language tend to make some efforts to teach their kids this foreign language. They help their kids as well to understand some basic maths. For an intelligent mum wants to make their child as intelligence as possible. This is not at the reach of mothers with scant intelligence.