Obsolete tuberculosis is not hereditary. Tuberculosis is only a respiratory infection and is not a genetic disease. The mother can transmit Mycobacterium tuberculosis to the fetus through the placenta, but this is only through a specific transmission route of TB and cannot be considered hereditary. Tuberculosis is highly contagious and can be transmitted to each other through close contact. There is some evidence, however, that there is a genetic susceptibility to TB, and that siblings who are related by blood can develop the disease sequentially or simultaneously, but it is rare for couples who are in regular close contact to develop the disease sequentially or simultaneously. This is only an indication that some people are more susceptible to TB than others under the same conditions, and does not indicate that TB is hereditary.