Is this a bug report?

Yes

Have you read the Bugs section of the Contributing to React Native Guide?

Yes

Environment

1. react-native -v:

react-native-cli: 2.0.1
react-native: 0.45.1

2. node -v:

v8.0.0

3. npm -v:

5.0.4

4. yarn --version (if you use Yarn):

0.24.6

Then, specify:

1. Target Platform (e.g. iOS, Android): Android
2. Development Operating System (e.g. macOS Sierra, Windows 10): macOS Sierra v10.12.5
3. Build tools (Xcode or Android Studio version, iOS or Android SDK version, if relevant): Nexus_5X_Android_7.1

Steps to Reproduce

1. Create a TextInput component without specifying autoCapitalize

Expected Behavior

I would expect both iOS and Android to autoCapitalize between sentences as that is the stated default in the documentation.

Actual Behavior

Only iOS autoCapitalizes between sentences. Android does not.

Reproducible Demo

Very, very simple to reproduce:

https://snack.expo.io/rkEgLks4-

You'll notice that by default the iOS keyboard autocaps between sentences and the Android keyboard does not.