I got into it with my mom over this! my brother is so anti government and vaccines and put in her head that shots cause autism. And I explained to them that its doesn't! my teacher a few yrs ago explained it like this. our genes are like switches, some are off while others are on, and sometimes the genes that are off can be turned back on by something, but if autism doesn't run in your family then there's nothing to worry about. and people think at one yrs old they would know if their child has autism or not but sometimes the child has to be older to make that diagnose..