This is ridiculous. How does this explain welfare moms with 7 children by 3 different fathers? They have no idea what their "income and life style" will be like tomorrow (because it all depends on the government). This must confuse you.
Too, you completely ignore the role of religion. Mormons and Catholics have large families for reasons which have nothing whatsoever to do with whether they "know their income and life style tomorrow".
Causes are todays liberal or right wing models of economy.
You seem confused. 1. I'll assume you are using "liberal" in the European sense, not the American sense (where it is usually used to mean leftist or socialist). 2. A model of the economy can't be "right wing" or "left wing". A model of the economy is either true or false. If it's true (i.e. the law of supply and demand) then what sense does a label like "right wing" or "left wing" make? 3. So I'll assume you meant to say not "model of the economy" but "economic policy" as in, laissez-faire (more or less). You blame what you call "right-wing" economic policy (namely, laissez-faire) for uncertainty about the future. 4. One problem is that we do not have a laissez-faire economy, by any stretch. Does 40-50 percent taxation with heavy regulation sound like laissez-faire to you? There is complete socialism for the poorest class. And that's here in the U.S., never mind the European "social democracies". So what are you talking about? 5. It is a fallacy to imply, as you do, that with left-wing economic policies (socialism) the people "know their income and life style tomorrow", but under "right-wing" policies (laissez-faire) they don't. People receiving government checks don't "know their life style tomorrow" because those government checks could change with every election. 7. It's more correct to say that people living under "left-wing" (socialist) economic policies don't take responsibility for their actions, because they have gotten used to the idea that the government takes care of them.
So, 8. In that sense you are correct to point out that "left-wing" economic policies encourage dependent people to have more children (because they are irresponsible) than "right-wing" policies do (because then people are responsible for their own behavior).