Why are blood relationships are less important in an industrial society than in a preindustrial society.?

Please Help, sociology!Why are blood relationships are less important in an industrial society than in a preindustrial society.?
Some would point to trust as the answer, In industrial societies there are institutions which enforce things like contracts and agreements which allow us to borrow, loan and engage in projects that are too large to do ourselves but benefit many of us. Things like building a house in any society requires the cooperation of many people. In a family or clan one person's exploitation of another member will result in sanctions by the other clan members. This threat of sanctions permits clan/family members to trust that the others will not take advantage of the other. One member exploiting another outside of the clan does not present an issue unless that other clan chooses to retaliate - which requires the cooperation of the other clan with respect to that outsider. I've read a few articles that suggest that this is what ';guanxi'; is, which is a means that many Chinese business transactions are done. Guanxi's use of close friends and family expedites business activities in the extremely corrupt Communist government. The trust from the relationships replaces (imperfectly) the strong tort and regulatory system that exists in the US.Why are blood relationships are less important in an industrial society than in a preindustrial society.?
Well in a preindustrial society everything is very face to face and personal. Everyone knows each other and class is very important - this is often dictated by blood relationships - you're born as part of the proletariat, you stay a member of the proletariat.





In an industrial society, there is much greater social mobility and so you can easily go from being a member of the proletariat to a member of the bourgeoisie.








Also, norms and values change. In an industrial society they are just seen as less important!








Hope this helps, will edit if you put what context in? EG family life, social classes, jobs etc