You're so badass, man. I wish I was more like you. Big, and strong, and tough, and the storm of innocent little children.
Yes, because it's totally not against the ToS.
Steam EULA:
When you complete Steam's registration process, you create a Steam account ("Account"). Your Account may also include billing information you provide to us for the purchase of Subscriptions. Accounts are only available to individuals over the age of 12.
If you are under the age of 13, a parent or guardian must obtain an Account on your behalf, and such parent or guardian agrees to
take full responsibility for all liabilities and obligations under this Agreement. You are solely responsible for all activity on your Account and for the security of your computer system.
You agree not to reveal your password to other users. If you permit others to use your Account, you are responsible for their illegal or improper use by such persons. Your Account and Subscription(s) are subject to the Agreement.