A study from Michigan State University shows that children who have lots of older brothers and sisters are the ones least likely to develop childhood asthma and other allergic diseases.

Nobody knows what causes asthma. A prevailing theory is that you have an immune system that is supposed to kill germs. If your immune system doesn't have a lot of germs to kill when you are very young, it starts attacking things that are not germs, such as pollen, dust, animal dander and foods. This study shows that children who have the most older brothers and sisters are the one least likely to suffer from allergies. Evidently when you have older siblings, you get lots of infections at a young age from the germs that they bring home from school, and killing these germs lets your immunity practice on germs, so it doesn't have to attack everything else. However, before you try to give your young child an infection, realize that this is just a theory, has not been proved yet, and may be wrong.

Does a higher number of siblings protect against the development of allergy and asthma? A review. Journal of Epidemiology and Community Health, 2002, Vol 56, Iss 3, pp 209-217. W Karmaus, C Botezan. Karmaus W, Michigan State Univ, Dept Epidemiol, 4660 S Hagadorn Rd, Suite 600, E Lansing,MI 48823 USA

Checked 8/9/05

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