Boku wa Imouto ni Koi wo Suru

It's similar to the last part of Yosuga no Sora, It has no erotic scenes, but still it's a catching love story. 

both involve incest but BokuImo is a shoujo manga adaptation(in later chapters of the manga-not in the OVA-it is revealed they are not actually siblings) and Yosuga no Sora is a bishoujo eroge adaptations(they are actual brother and sister)...also Yosuga no Sora has fanservice while BokuImo,being a shoujo,has almost none 

Because there is a "forbidden" relationship - sister x brother. 

Both story is about incest. 

-Taboo relationships. -Sex scenes -Dramatic love "twincest" 

Both have incestuous relationship , with Sora one being more lustful. Boku wa Imouto is more oriented toward Love/romance.  

Because incest obviously, and generally sad mood and melancholic soundtracks that portray it.  

Koi Kaze and Boku wa Imouto ni Koi wo Suru are an obvious match. Not only do they both deal with the same tricky and potentially controversially the subject matter, that of incest, as they approach it in a sober, thoughtful manner that pulls at the heartstrings. Both are realistic and do not use fanservice, these anime are all about the emotional reaction of these characters who find themselves in a compromising situation.  

Incest, either love it or hate it. Personally, I find the characters in Koi Kaze easier to relate to due to the length of the series, but they both made me cry. ^^" 

I strongly urge fans of Boku Wa Imouto ni Koi wo Suru to watch Koi Kaze. Both shows deal with the topic of incest, specifically a romantic love between brother and sister, but Koi Kaze actually brings up legitimate issues that could arise if siblings decided to become a couple. There's no peer approval, no understanding family members, no marriage, no 'love-finds-a-way', only a strong rejection from society. Additionally, Koi Kaze analyzes realistically the psychological profile of a brother that falls in love with their sister (and vice-versa) without sugar-coating it; the heavy mental pitfalls that befall the pair - a mixture of self-loathing and never-ending anxiety - are a hard, but refreshing, watch. If you want to see the incest taboo explored to its full depth with masterful, mature lens, watch Koi Kaze. read more 

Both shows take a sober, respectful look at brother-sister incest romances, and take the conflicting feelings seriously. Boku wa Imouto ni Koi wo Suru is just an OVA, so the characters are less developed, and unfortunately it has an "read the manga" ending. Koi Kaze is one cour TV and adds an age gap on top of the incest. Neither of the shows is fan service pandering or has ecchi elements, yet both deal with actual sex between the lovers. In Koi Kaze the male is torn and suffering and the female is fueling their romance towards physical love, in Boku wa imouto it's the other way around. read more 

Both of these series involve incestual relationships with the MC and their sister. 

Both are OVAs centring around the forbidden attraction between a brother and sister in a highly dramatic and angsty fashion. Although Angel Sanctuary has the whole apocalypse thing to divvy the plot's attention between, its focus on the earliest parts of the manga allows the forbidden love component to take nearly as big a role as it does in BokuImo. 

both anime have incest relationship, but Aki-Sora have more funservice