It is National Ethical Investment week. When the merits of putting your money into firms that promote sustainable living are highlighted.
But what are the financial returns if you do decide to invest in 'sin' stocks? Two American academics have looked into this and say investor returns can be up to 2.5% higher than comparable stocks.
Co-author of 'The Price of Sin', Professor Harrison Hong at the Economics and Finance department at Princeton University explains why.
Stephen Hine, head of responsible investment development at EIRIS, also joins the programme.