By default the Title  of a SharePoint Team Site does not show the site inheritance (e.g. Root Site->Parent Site->Current Site will only show Current Site).

To show this inheritance, replace:

<SharePoint:SPLinkButton runat="server" NavigateUrl="~site/" id="onetidProjectPropertyTitle"><SharePoint:ProjectProperty Property="Title" runat="server" /></SharePoint:SPLinkButton>

With

<asp:SiteMapPath      

runat="server"      

SiteMapProviders="SPSiteMapProvider,SPXmlContentMapProvider"      

RenderCurrentNodeAsLink="false"      

NodeStyle-CssClass="breadcrumbNode"      

CurrentNodeStyle-CssClass="breadcrumbCurrentNode"      

RootNodeStyle-CssClass="breadcrumbRootNode"      

HideInteriorRootNodes="true"      SkipLinkText=""/>

Source: http://sharepoint.stackexchange.com/questions/11480/breadcrumb-not-showing-parent-site