I would be more concerned about the effect of accepting the $35,000 gift on your relationship with your in-laws than other relatives. It is unclear to me whether you are living with your in-laws, or just living in an extra house they own. Assuming it is an extra home, they fact your in-laws have an extra house lying around and are willing to give a $35,000 gift, they are not hard up on cash and will support their other children (if any) in similar ways as they are supporting your husband (and you). The gift is between you and them, and need not concern others. If the $35,000 is a significant chunk of their net worth, then I would be a bit more concerned about the relationships with other relatives.
Even if $35,000 is peanuts to your in-laws, you should be concerned about how accepting that gift affects your relationship with them. Rarely are family gifts truly "no strings attached." What are the strings going to be? Expectations to help the parents in the future? Help other family members? Will they expect you to be at every family event without fail? Will the in-laws feel entitled to know the details of your personal finances? Will they render unsolicited and unwanted opinions on how you should use your money? Really look closely at this question, as it should determine your answer as to whether you accept the gift. If you are lucky enough to have in-laws who respect boundaries and are capable of giving no-strings-attached gifts, then go for it. If not, proceed with extreme caution, as your freedom and the strength of your marriage are more important than a $35,000 windfall.
Also, its not really your problem, but your parents should be aware of the gift tax consequences. The $35,000 gift would exceed the $14,000 annual exemption and will at least trigger gift tax reporting obligations, and perhaps gift tax liability (though this is unlikely unless your in-laws are very wealthy).