Why move Country

My text is about reasons why people move from their birth country with the top 3 reasons being war and politics, natural disasters and the biggest reason is that some countries are richer then others and you get more opportunities in other countries then in your birth country. Some people return to their birth country when they have made enough money or when its safe to move home but others stay in their new country for the rest of their lifes. Some inhabitants blame the migrants for taking their jobs. Its good ina biological level to as the gene pool needs new influences ro remain healthy so its good that many different people share a country.