When the census taker comes to the door, he asks "how many people are in your household?"
And we do not exclude infants from that count.
So of course infants are members of a household.
Here's a nice site I just found...
If some would fault this construction for taking away with one hand what’s been given with another, keep in mind that these are not the words of man, but God. He said these things and He is not lacking in internal consistency or harmony."To this end pastors ought to exhort the flock to claim and trust God’s covenant promises for their families keeping in mind that those promises are not in opposition to His sovereign decrees, and that “not all (are) Israel who are descended from Israel,” “nor are they all children because they are Abraham’s descendants;” that it is “not the children of the flesh who are children of God, but the children of the promise are regarded as descendants;” that “Jacob I loved, but Esau I hated;” and that all this is done in such a way that “There is no injustice with God” when He says “I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.”
This one from the same site also looks good...
Why must it be assumed infants are in the house? What rational evidence exists?