Should politicians own businesses?

over the years, there has been a lot of controversies over the fact that highly influential people, especially those in the government sector, who own businesses.
Although this would not be deemed as a problem, when it comes to major issues such as taxes and so forth, it becomes easy for them to put in their influence into play, since after all, they do know who's who in the economy.
But is it really fair? Should these politicians own these businesses while they are in office, or wait until they step down? In most situations they do not need for anything, they get free housing,transportation, and sufficient salaries. these businesses are not run by them, and even if the creation of business is important in a country, especially in my own Botswana, is it worth the corruption involved, and lack of ethics?
I say that politicians need to finish their tenor in office and only then think of taking on businesses, although even in that situation, they will still have a form of influence, it would not be as high, and we cannot exactly say they should not go into business altogether, because not all the tomatoes in the basket are rotten.