This is a fasincating piece of research by HubSpot that digs into the data driving behaviour based on generational differences.  

They specifically look at the millennial generation which are now moving into buying homes, baby products and more 'grown up' products but how they're searching for such items is clearly different to how an oldie like me would buy.

The 18-24 group are driving the mobile device trend.  They're more likely to trust Google and a Facebook friend than an email.  They want videos, photos and social posts.  Quite clearly, email is not the way to reach this audience in the future.