Is triple negative type breast cancer hereditary? or can it be caused by stress and overweight?

Maybe: The majority of brca1 positive patients that get breast cancer have triple negative breast cancer. Overweight patients may have tougher time breathing but a chest xray or other imaging for stating may be indicated for treatment of triple negative disease. There are many clinical trials available for this disease and they usually include a thorough staging workup.

Maybe and no: Neither stress nor obesity cause breast cancer of any type. Triple negative does have some hereditary component but many women get it without any family history of breast or other cancers.