Family history rarely lives in one person's memory alone. A sibling might remember a grandparent's stories differently, or a cousin might be holding onto documents you have never seen. MyOrigins lets you invite relatives to contribute directly to the same tree, and lets you share specific categories of your own research with other MyOrigins users.
Inviting a contributor gives them their own space to add stories and documents tied to the people you are both researching - it does not hand them your account or your login. Sharing with another MyOrigins user works differently: you choose which categories of research to share (vital events, land records, and so on), and only those categories become visible to them.
Nothing is shared automatically. Every invitation and every share is something you start yourself, and you can see exactly who has access to what from the Sharing page at any time.