I plan to create a custom theme and I was wondering is it bad to use the same theme on tumblr, google+,facebook & twitter even though it's a theme that I made? does using the same theme effect SEO?
I don't think using the same theme has any impact on SEO, positive or negative. A theme is not like content where you can get penalized for having the same content on several different sites. Using the same theme on all your sites help increase the relevance of your sites, but this is from a user's point of view and not a search engine's. Hope that helps. Have a good day!
It certainly wouldn't effect your SEO, It is the quality of the content that will count. When you consider some of the poor designed ranking websites, it is plane to see. Using the same theme would give you continuity throughout your branding, so I think it is a good idea. Also as far as aesthetic maintenance goes, you are making your job a whole lot easier! Good luck buddy
nope. you're safe with that. at least now, you won't be affected as this is a part of the visual branding. But who knows what evil the new Google update will bring.
Using the same theme for all these channels is a good idea for building a brand! But it can't help your site or channels to carry out better search engine ratings. Content optimized for certain keywords can only help in terms of SEO.