Indians how true is it that you should Never partner in business with family or friends?

I'm in Europe now. My cousins have very successful plywood, laminates and Hardware business in our town. and they are looking forward to expand their business in tier 2 city in India. I have no knowledge about this business, but they are asking me to come back to India and join their business. They earn daily around 10k-20k rupees. During season more than that. Very tempting. They are calling me because they trust me because I have always been very smart and have good communication skills. I am in Europe since last 3 years and also speak the local language and applying for jobs here. Shall I move back to India and join the family business or continue for looking for job here in Europe?