It is only in the last one hundread years that the custom of the nuclear family became widespread. Most of the immigrants to america , such as those from Ireland and Italy , also had the custom of the extended family , and when most americas made their living as farmers , it was easy for the extended family to stay together. However , since most people in industrial countries now work for some kind of business , and since it is so common to move to a new city to get a good job , now people in these countries frequently live only with their own spouses and children .