Regarding Hepatitis A, B, C--how contagious are they? Please answer for each one.?

The reason I ask, is a friend of mine has a relative that has Hep B, and was told it's very contagious, and she likes to stick her finger in foods to check(?) like a pan of chili, etc.

Hi SAK,
Hepatitis A is food and water borne and it can be transmitted via the oral-fecal route. Hence if someone is infected with the Hepatitis A virus they can transmit the disease by dipping their hands into food. It can be transmitted via oral sex as well because of the proximity of the fecal and sexual organs.

Hepatitis B is transmitted via body fluids like blood, semen, vaginal secretions. It cannot be transmitted by saliva or tears, so no fear of food tasting with fingers. So it can be transmitted by sharing toothbrushes, razor blades, syringes and sexual contact.

Hepatitis C is transmitted solely via the blood. It can be spread by sharing syringes, toothbrushes and razor blades. Vigorous sexual acts that may cause a tear in the skin or membranes can help transmit the virus.

I think your over reacting. Now, with that being said
I would worry about Hepatitis A given the example you have provided.
Hepatitis A is food born. It can pass along to others by sticking your finger in the cooked foods after not washing hands correctly. It is spread via exposure to fecal matter that ends up in water and food.
Hepatitis B is spread through all bodily fluids, but is more hard to catch via saliva. A heat source is likely to kill off any germs.
HCV is only acquired if the person is bleeding and you have an open wound. (blood to blood only)