[...] For most of human history, height remained relatively stable. Until 1800, the average height in Europe hovered between 165 cm and 170 cm, but over the past 200 years something remarkable has happened: heights, globally but particularly in Europe, have increased dramatically. Many European countries saw increases in average heights of over 15 cm, and this has been especially evident in the Netherlands – the average Dutch man has grown from 166 cm in 1810 to 184 cm today, an increase of 18 cm in just two centuries. Dutch men are currently the tallest in the world.
[...] Recent research shows that long-lasting or recurring illnesses were associated with shorter adult heights in the Netherlands in the 19th century, while shorter, one-off periods of illness may have actually been helpful for growth. This is likely because less severe illnesses boosted immunity against future infections.
The deaths of parents, particularly of mothers, have also been shown to result in shorter heights. For very young children, this would have been because they depend on their mothers for nutrition, but it was also true for older children, indicating the profound stress of losing a primary caregiver.
Curiously, although losing a mother was linked to shorter children’s heights – in the Netherlands and elsewhere – losing a father was not, potentially due to the gendered nature of parental care in this period.
Evolution (natural selection) doesn't work that way though. That would only work if either people started only having kids with shorter people, or those stresses you're taking about caused people to die before having kids, which I didn't think is happening.